Traditional small electric motors, especially fractional horsepower motors, are usually air cooled by an axial fan mounted on the rotor shaft to generate a flow of air. Because of the fan, the size of the motor is increased and the efficiency of the motor is decreased.
Further more, in specified applications, there is not enough space for a channel or passage within the motor or stator for the air flow, preventing the heat from dissipating quickly.
Hence there is a desire for a small size electric motor with improved cooling.